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From Josh Elser <els...@apache.org>
Subject Re: Fwd:
Date Wed, 02 May 2018 03:04:34 GMT
FYI, the mailing list strips images.

There is only one BlockCache per RS. Not sure if that answers your Q1 in 
entirety though.

Q2. The "Block" in "BlockCache" are the blocks that make up the HBase 
HFiles in HDFS. Data in the Memstore does not yet exist in HFiles on 
HDFS. Additionally, Memstore is already in memory; no need to have a 
different cache to accomplish the same thing :)

On 5/1/18 9:25 PM, Xi Yang wrote:
> Sorry to bother you guys. May I ask 2 questions about HBase?
> 
> Q1
> 
> I found that |HFileScannerImpl.getCachedBlock(...)| get block from 
> BlockCache. This CachedBlock is used by |StoreFileScanner|. Is that mean 
> the read model like:
> 
> *Model A*
> 
> Or there is only one BlockCache and all the read request will go through 
> it first, like:
> 
> *Model B:*
> 
> ​
> Q2
> If the data been read from Memstore, will it be put in BlockCache to 
> accelerate the read process next time?
> 
> ​
> Thanks,
> Alex
> 
> ​

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